Hybrid mechanical and solar energy harvesting

Citation

(2012), "Hybrid mechanical and solar energy harvesting", Sensor Review, Vol. 32 No. 2. https://doi.org/10.1108/sr.2012.08732baa.006

Hybrid mechanical and solar energy harvesting

Article Type: Nanosensor update From: Sensor Review, Volume 32, Issue 2

The following part of this update concerns the application of nanomaterials to solar energy harvesting but a link between the seemingly disparate fields of photovoltaics (PV) and NGs has been demonstrated by the Georgia Tech group. They have successfully developed a hybrid structure that simultaneously harvests solar and mechanical energy, a concept first reported in 2005, and the latest development of this was described in a 2011 paper (Xu et al., Advanced Materials, 23, pp. 873-7). Using aligned ZnO nanowire arrays grown on the surfaces of a flat substrate, a dye-sensitised solar cell (DSSC) is integrated with a piezoelectric NG. The DSSC harvests solar energy falling on the top of the structure and the NG harvests ultrasonic wave energy from the surroundings. These two energy harvesting approaches can work simultaneously or individually and can be integrated in parallel or serial to raise the output current or voltage, respectively, as well as the power. When only the DSSC component was in operation and under full sunlight illumination, the optimum output power density was found to be 32.5 μWcm⁻² but when the DSSC and the NG were simultaneously operating in serial connection, the corresponding output power density was 34.5 μWcm⁻². Thus, an increment of 2 μWcm⁻² was achieved by activating the ultrasonic wave, which yielded an enhancement in the optimum power of over 6 per cent. The system is shown in Figure 6.

Figure 6 (a) Schematic of the hybrid PV-NG device which is illuminated by sunlight from the top and excited by ultrasonic waves from below; the ITO layer on the DSSC part and the GaN substrate act as the cathode and anode of the device, respectively, (b) schematic of a solid-state DSSC, (c) schematic of a vertically aligned ZnO nanowire array grown on a GaN substrate (d) top view SEM of the DSSC; (e) SEM image of the as-grown ZnO nanowire array